The invention relates to carbon blacks, methods of producing carbon blacks and methods by which carbon blacks are used.
EP 0 569 503 teaches a method for the surface modification of carbon-containing material with aromatic groups by electrochemical reduction of a diazonium salt. It also known that carbon blacks (xe2x80x9cblacksxe2x80x9d) can be linked to organic groups by a diazonium group produced via the primary amine (WO 96/18688).
The known methods have the following disadvantages:
An alkyl group or preferably an aryl group is required as a linking group; the modification therefore always takes place at a rather distant interval from the carbon black surface. A direct screening of the carbon black surface with closely applied polar groups is impossible. The modification does not take place in the immediate vicinity of the surface.
The carbon black is contaminated with acids and/or salts. In addition to the actual modification reagent, additional acids must be used in order to adjust the pH. These acids are not bound to the carbon black but rather constitute an impurity in the carbon black or must be removed by purification steps.
The non-ionic, organic nitrites that can also be used for diazotization are poisonous and readily combustible. Groups of the nitrites (counterions, alkyl groups) remain unbound as contaminants in the carbon black.
The use of nitrite in an acidic medium is required to carry out the diazotization. Poisonous nitrogen oxides can develop from this.
The modification by means of diazonium salts takes place primarily in aqueous phase. Due to the high evaporation enthalpy of water, the subsequent necessary drying requires a high expenditure of energy, resulting in substantial expense.
Black pigments may be produced by the cycloaddition of 1-methylene-4,8-dioxaspiro [2.5]octane-4,8-dioxaspiro[2.5]oct-1-ene derivatives and/or 2,3-diazabicyclo-[2.2.1 ]hept-2-ene derivatives on the black surface (JP 11315220). However, this process is expensive and has the disadvantage of possible instability of C3 rings.
It is an object of the present invention to provide a carbon black with organic groups, wherein:
the polar groups directly screen the surface;
the modification of the carbon black is sufficiently variable that the groups can be directly over the surface and/or far removed from it;
the modification takes place in the direct vicinity of the surface;
the resulting carbon black is not contaminated by acids, salts and the like, so that no purification is required;
the carbon black does not have to be dried with a high expenditure of energy;
no poisonous waste gases are produced during the modification;
no solvents or only slight amounts of solvents that can be readily removed are required;
the modification is possible without solvents; and
the modification can be carried out with the simplest compounds possible.
The invention has as subject matter a carbon black with organic groups, characterized in that the organic groups are connected to the black via at least one or two carbon atoms of the Cxe2x80x94C single bond or double bond that are not a component of an aromatic system, contain at least one activating substituent on at least one carbon atom of the Cxe2x80x94C single bond or double bond and contain no cyclic C3 structure or 2,3-diazabicyclo[2.2.1]hept-2-ene.
Activating substituents can be, for example, acceptor substituents. Acceptor substituents can be xe2x80x94COOR, xe2x80x94COxe2x80x94R, xe2x80x94CN, xe2x80x94SO2R, xe2x80x94SO2OR, xe2x80x94COxe2x80x94Xxe2x80x94COxe2x80x94, with Rxe2x95x90H, alkyl, aryl or functionalized alkyl or aryl,
Xxe2x95x90O or Nxe2x80x94R5,
R5=alkyl, Y-functionalized alkyl, polymers, cyclic organic groups, aryl or Y-functionalized aryl of the form Arxe2x80x94Yn (n-1-5), Y=xe2x80x94OH, xe2x80x94SH, xe2x80x94SO3H, xe2x80x94SO3M, xe2x80x94B(OH)2, xe2x80x94O(CH2xe2x80x94CH2xe2x80x94O)nxe2x80x94H, xe2x80x94COOH, xe2x80x94COOM, xe2x80x94NH2, xe2x80x94NR2, xe2x80x94N((CH2xe2x80x94CH2xe2x80x94O)nH)2, CON((CH2xe2x80x94CH2xe2x80x94O)nH)2, trialkoxysilyl, perfluoroalkyl, R5, xe2x80x94NH3+, xe2x80x94NR3+, xe2x80x94SO2xe2x80x94NR2, xe2x80x94NO2, xe2x80x94Cl, xe2x80x94COxe2x80x94NR2, xe2x80x94SSxe2x80x94 or xe2x80x94SCN, M=metal, e.g., alkali+ or alkaline earth++.
The carbon black used can be any known black such as, e.g., furnace black, gas black, channel black, flame black, thermal black, acetylene black, plasma black, inversion blacks (known from DE 195 21 565), Si-containing blacks (known from WO 98/45361 or DE 19613796), metal-containing blacks (known from WO 98/42778), arc blacks and blacks that are the byproducts of chemical production processes. The black can be activated by established reactions. Blacks can be employed that are used as reinforcement filler and rubber mixtures. Colored blacks can be used. Other blacks can be: conductivity black, black for UV stabilization, black as filler in other systems than rubber such as, e.g., in bitumen, plastic, black as reducing agent in metallurgy.
The primarily applied groups can be further modified by subsequent reactions.
It is a further object of the invention to provide a carbon black having an organic group. This carbon black can be obtained by reacting the black with organic compounds containing a Cxe2x80x94C double bond or triple bond, the Cxe2x80x94C double bond or triple bond which is activated by at least one substituent. The organic group should contain no cyclic C3 structure or 2,3-diazabicyclo[2.2.1]hept-2-ene.
A further object of the invention is to provide a method of producing a carbon black of the invention. This method is characterized in that black is reacted with organic compounds containing a Cxe2x80x94C double bond or triple bond, the Cxe2x80x94C double bond or triple bond of which is activated by at least one substituent and in that the organic group contains no cyclic C3 structure or 2,3-diazabicyclo[2.2.1]hept-2-ene. Organic compounds containing a Cxe2x80x94C double bond or triple bond that can be used comprise all compounds that carry suitable acceptor substituents for activating the multiple bonds.
The substituents can be tailored to suit the potential areas of application since the reaction principle discovered permits the introduction of hydrophilic as well as lipophilic groups. The groups can also be reactive ionically, polymerically or for further reactions.
Organic compounds with acceptor substituents can be compounds of formula I, in which R1, R2, R3 and R4 can be the same or different 
with R1=xe2x80x94COOR, xe2x80x94COxe2x80x94R, xe2x80x94CN, xe2x80x94SO2R, xe2x80x94SO2OR,
R2, R3, R4=R1, H, alkyl, aryl, xe2x80x94COOM with M=H+, alkali+, alkaline earth++, Cl and other non-acceptor substituents and
Rxe2x95x90H, alkyl, aryl or functionalized alkyl or aryl such as, e.g., xcfx89-carboxyalkyl, carboxyaryl, HSO3-alkyl-, H2N-alkyl-, H2N-SO2-alkyl-, HSO3-aryl-, H2N-aryl-, H2Nxe2x80x94SO2-aryl- and similar groups.
Maleic acid anhydride and maleic acid imides of general formula II can be used as organic compounds (II) 
The group R5 be as defined above or it can:
be an aliphatic group, a cyclic organic group or an organic compound with an aliphatic part and a cyclic part,
be substituted or unsubstituted, branched or unbranched, comprise an aliphatic group, e.g., groups of alkanes, alkenes, alcohols, ethers, aldehydes, ketones, carboxylic acids, hydrocarbons,
be a cyclic compound, e.g., alicyclic hydrocarbons such as, e.g., cycloalkyls or cycloalkenyls, heterocyclic compounds such as, e.g., pyrrolidinyl-, pyrrolinyl-, piperidinyl or morpholinyl, aryl groups such as, e.g., phenyl, naphthyl or anthracenyl, and heteroaryl groups such as, e.g., imidazolyl, pyrazolyl, pyridinyl, thienyl, thiazolyl, flryl or indolyl,
be substituted by further functional groups,
be a chromophoric group or a dye.
Unsaturated compounds such as, e.g., p-benzoquinone or ethylvinyl ether can be also used as the organic compound with acceptor substituents.
For compounds according to formula II with Xxe2x95x90O, there is the possibility of subsequently functionalizing the products of the type of substituted succinic acid anhydrides, e.g., by basic or acidic ring opening, by semi-ester formation with alcohols or alcoholates as well as by amide formation with amines and subsequent thermal imidization in the case of primary amines. When ammonia is used, accumulating imides can also be subsequently substituted on the nitrogen.
The organic compound with acceptor substituents can be applied on the black by being mixing in or sprayed on. The organic compound with acceptor substituents can be applied as powder, melt or solution. It is especially advantageous if the organic compound with acceptor substituents is applied during the production of the black, during which the addition of the organic compound takes place at a location exhibiting the necessary temperature.
The reaction for modifying the black can preferably be carried out without solvent or in a solvent, preferably a readily volatile, organic solvent. The reaction for modifying the black can take place by tempering. Modification can take place at temperatures of 0xc2x0 to 250xc2x0 C, preferably from 80xc2x0 to 140xc2x0 C.
The blacks in accordance with the invention can be used, e.g., as filler, reinforcing filler, UV stabilizer, conductance black or pigment in rubber, plastic, printing inks, inks, inkjet inks, paints and dyes, bitumen, concrete and other construction materials or paper. They can also be used as reducing agents in metallurgy.
The blacks of the invention have the advantage that:
Blacks modified in a polar manner (e.g., with xe2x80x94SO3xe2x80x94 groups) can be better dispersed in polar systems such as water,
Blacks modified in a non-polar manner (e.g., with alkyl groups) can be better dispersed in non-polar systems such as, e.g., oils,
Suitably modified blacks with polar or sterically bulky groups are stabilized in the systems electrostatically or sterically,
Blacks modified in accordance with the method of the invention are better stabilized in dispersions and thus exhibit better coloristic properties such as color depth and bluishness,
Blacks with bound dyes or chromophoric groups exhibit altered color tones,
Blacks with substituents that continue to be reactive can be used for coupling and cross-linking in systems (e.g., rubber),
Reactively modified blacks make it possible to bind the black to the polymer,
Blacks can be produced that are low in byproducts, salts, acids and moisture,
The polar groups directly screen the surface,
The modification of the black is so variable that the groups can be directly over the surface and/or also very far removed,
The modification takes place in the immediate vicinity of the surface.